The present invention relates to a thin film evaporating device and, more particularly, a thin film evaporating device comprising a housing defining space for receiving a plurality of elongated tubular evaporators.
Thin film evaporators of the type described above may be used for the concentration of flowable, temperature-sensitive, and/or coating-forming materials. All of them are based on the principle of creating a thin product layer in the interior of a heated cylinder by means of a rotating rotor, so that the heat supplied to the cylinder wall leads to evaporation of the portion of the liquid with a low boiling point, the vapor only having to travel a short distance through the product. With this arrangement it is possible to concentrate mixtures of liquids with different boiling points, and also liquids containing solids. The rotor has vanes which are separated from the heated inner wall of the evaporator by a gap of only a few millimeters. Alternatively, the cylinder is equipped with movable wiper blades, so that the product running over the heated inner wall of the evaporator may be kept in a thin product film. Up to now the evaporator has been heated by making the tubular part double-walled, the intermediate space between the inner wall and the outer wall then being supplied with a heating medium, for example steam. The throughput capacity of evaporators of this type may be controlled only within narrow limits.